1. Field of the Invention
The present invention relates to a motion detection apparatus and method, for providing information about whether there is motion in an image to a device for separating a luminance signal and a chrominance signal from a composite video signal. More particularly, the present invention relates to a motion detection apparatus and method for accumulating information about whether there has been motion in images from a past frame to the previous frame, and using the accumulated information as a threshold value when determining whether there is motion in an image of the present frame, in consideration of whether there is motion in a black-and-white image and whether there is color motion in a color image.
2. Description of the Related Art
A video signal generated by a photographing device may be subjected to a signal processing operation, e.g., modulation, and then transmitted to a display device through a wired or wireless channel. The display device may restore the received signal through a signal processing operation, e.g., demodulation, and display an image corresponding to the restored signal on a screen.
An RGB signal generated by the photographing device may be transformed into a luminance signal (Y signal) and a chrominance signal (C signal) by a transformer, according to the type of the signal transmission system (for example, a National Television System Committee (NTSC) system or a Phase Alternation by Line (PAL) system). The C signal may be divided into U and V signals or I and Q signals according to the type of the signal transmission system.
To transmit the video signal through the channel, the Y and C signals may be synthesized to produce a composite video signal. The composite video signal may include a plurality of frame signals. A single frame signal may include data (referred to as “one frame image data” hereinafter) about an image (one frame image) displayed on a screen for a unit of time (that is, one frame). The one frame image data may be composed of a plurality of line data units each including a plurality of column data units. One line and one column may define one pixel. When the one frame image data is composed of X*Y pixel data, for example, the one frame image data includes X line data units each including Y column data units.
To separate Y and C signals corresponding to a certain pixel from the composite video signal, pixel data adjacent the certain pixel in time or location may be used. When there is no motion in an image, using temporally adjacent pixel data may provide the most accurate separation. When there is motion, using temporally adjacent pixel data may result in a large error, so spatially adjacent pixel data may be used instead. Therefore, motion detection may be used to select an appropriate separation.
However, conventional motion detection only detects whether there is motion in an image based on the amplitude of the composite video signal (for example, the sum of the amplitudes of Y, U and V signals), without considering the individual components of the composite video signal (for example, the individual Y, U and V signals). As a result, no motion in an image may be detected even when the respective amplitudes of the Y, U and V signals vary, but the sum of the amplitudes of the Y, U and V signals does not vary. Thus, temporally adjacent pixel data may be inappropriately used to separate Y and C signals from the composite video signal, which may result a large error.